The present invention is related to a system and method for providing control in a vehicle, such as a locomotive or a transit vehicle, propelled by traction motors, and, more particularly, to a system and method for providing motor excitation frequency control and wheel slip control without using sensors for measuring rotational speed of the motor.
Locomotives used for hauling applications have been generally equipped with speed sensors, e.g., electromechanical sensors or tachometers, coupled to respective traction motors or to the axles driven by the motors. The speed sensor data or information may be used to provide motor control since the speed information provided by the speed sensors may be readily used to derive a respective excitation frequency signal for the traction motors. It will be appreciated that the overall motor control reliability partly depends on the reliability of the speed sensors since if, for example, the reliability of the speed sensors is compromised, then the overall motor control reliability will be similarly compromised. It will be further appreciated that having to use such speed sensors adds to the overall cost of the motor control system in view of the cost of the sensors themselves and any associated wiring.
In view of the above, it would be desirable to provide a processor system using motor control techniques which would allow for computing the motor excitation frequency without having to use speed information from such speed sensors while maintaining effective wheel slip control. It would be further desirable to provide a processor system using motor control techniques no longer dependent on the reliability of electromechanical speed sensors and thus enhancing the overall reliability of the control system while resulting in reduced costs.